Global warming

Iris hypothesis

Lindzen hypothesized that the Earth may act like an infrared iris; increased sea surface temperature in the tropics would result in reduced cirrus clouds and thus more infrared radiation leakage from Earth's atmosphere.[8] This hypothesis suggests a negative feedback which would counter the effects of CO2 warming by lowering the climate sensitivity. Satellite data from CERES has led researchers investigating Lindzen's theory to conclude that the Iris effect would instead warm the atmosphere.[9][10]

NAS panel

In 2001 Lindzen served on an 11-member panel organized by the National Academy of Sciences.[11] The panel's report, entitled Climate Change Science: An Analysis of Some Key Questions,[12] has been widely cited. Lindzen subsequently publicly criticized the report summary for leaving out doubts about the weight that could be placed on 20 years of temperature records.[13]

IPCC activities

Lindzen worked on Chapter 7 of 2001 IPCC Working Group 1, which considers the physical processes that are active in real world climate. He had previously been a contributor to Chapter 4 of the 1995 "IPCCSecond Assessment." He described the full 2001 IPCC report as "an admirable description of research activities in climate science"[14] although he criticized the Summary for Policymakers. Lindzen stated in May 2001 that it did not truly summarize the IPCC report[15] but had been amended to state more definite conclusions.[16] He also emphasized the fact that the summary had not been written by scientists alone. The NAS panel on which Lindzen served says that the summary was the result of dialogue between scientists and policymakers.[17][18]

Statistical significance of recent warming

Writing in Newsweek in 2007, he stated "warming has largely occurred during the periods from 1919 to 1940 and from 1976 to 1998, with cooling in between. Researchers have been unable to explain this discrepancy." [19] In a paper presented to the Competitive Enterprise Institute Lindzen referred to the "warming episode from the mid-1970s to the mid-1990s" and the "fact that the global temperature anomaly ceased increasing by the mid nineties" as evidence against climate models.[20] An open letter to United Nations Secretary-General Ban-Ki Moon, signed by Lindzen includes the statement "there has been no net global warming since 1998. That the current temperature plateau follows a late 20th-century period of warming is consistent with the continuation today of natural multi-decadal or millennial climate cycling."[21] More recently, he has stated that there has been no statistically significant warming since 1995, and restated this as "warming has ceased for the past fourteen years".[22][23]

Media appearances

Lindzen has contributed to several articles on climate change in the mainstream media. In 1996, Lindzen was interviewed by William Stevens for an article in the New York Times.[24] In this article, Lindzen expressed his concern over the validity of computer models used to predict future climate change. Lindzen said that computer models may have overpredicted future warming because of inadequate handling of the climate system's water vapor feedback. The feedback due to water vapor is a major factor in determining how much warming would be expected to occur with increased atmospheric concentrations of carbon dioxide. Lindzen said that the water vapor feedback could act to nullify future warming. According to Stevens, some scientists who worked on computer climate models did not accept Lindzen's nullification hypothesis.

The New York Times article included the comments of several other experts. Jerry Mahlman, director of the Geophysical Fluid Dynamics Laboratory at Princeton University, did not accept Lindzen's assessment of the science, and said that Lindzen had "sacrificed his luminosity by taking a stand that most of us feel is scientifically unsound." Mahlman did, however, admit that Lindzen was a "formidable opponent." William Gray of Colorado State University basically agreed with Lindzen, describing him as "courageous." He said, "A lot of my older colleagues are very skeptical on the global warming thing." He added that whilst he regarded some of Lindzen's views as flawed, he said that, "across the board he's generally very good." John Wallace of the University of Washington agreed with Lindzen that progress in climate change science had been exaggerated, but said "relatively few scientists who are as skeptical of the whole thing as Dick [Lindzen] is." Stephen Schneider of Stanford University criticized Lindzen's estimate of climate sensitivity (the global mean temperature increase associated with a doubling in atmospheric carbon dioxide concentrations), arguing that it was too specific given the available evidence. Lindzen's reply to this was that he had at least given reasons for his estimate, rather than following the "herd instinct" common in science.[24]

In June 2001, Lindzen wrote an article for the Wall Street Journal, stating that "there is no consensus, unanimous or otherwise, about long-term climate trends and what causes them" and "I cannot stress this enough – we are not in a position to confidently attribute past climate change to carbon dioxide or to forecast what the climate will be in the future. That is to say, contrary to media impressions, agreement with the three basic statements tells us almost nothing relevant to policy discussions."[13] In July, Lindzen was interviewed by Fred Guterl for Newsweek.[25] Other experts also contributed to the article. Contrary to the IPCC's assessment, Lindzen said that climate models were inadequate and had not improved. Guterl wrote that despite the accepted errors in their models, e.g., treatment of clouds, modelers still thought their climate predictions were valid. Lindzen gave an estimate of the Earth's climate sensitivity of less than 1 degree Celsius. Lindzen based this estimate on how the climate had responded to volcanic eruptions. James E. Hansen, a climate scientist at the Goddard Institute for Space Studies estimated a climate sensitivity of 3–4 degrees Celsius. Hansen based this estimate on evidence from ice cores. According to Hansen: "Dick's idea that climate sensitivity is low is simply wrong, [...] The history of the earth proves him wrong."[25]John Schellnhuber, director of the Potsdam Institute for Climate Impact Research, took the view that greenhouse gas emissions should be cut. When asked about Lindzen, Schellnhuber said "People like him are very useful in finding the weak links in our thinking."[25]

In September 2003 Lindzen wrote an open letter to the mayor of his home town, Newton, Massachusetts,[26] his views on global warming and the Kyoto Accord, in which he stated, "... [T]he impact of CO2 on the Earth's heat budget is nonlinear. What this means is that although CO2 has only increased about 30% over its pre-industrial level, the impact on the heat budget of the Earth due to the increases in CO2 and other man influenced greenhouse substances has already reached about 75% of what one expects from a doubling of CO2, and that the temperature rise seen so far is much less (by a factor of 2–3) than models predict (assuming that all of the very irregular change in temperature over the past 120 years or so—about 1 degree F—is due to added greenhouse gases—a very implausible assumption)."

The November 10, 2004 online version of Reason magazine reported that Lindzen is "willing to take bets that global average temperatures in 20 years will in fact be lower than they are now."[27]James Annan, a scientist involved in climate prediction, contacted Lindzen to arrange a bet. Annan and Lindzen exchanged proposals for bets, but were unable to agree. Lindzen's final proposal was a bet that if the temperature change were less than 0.2 °C (0.36 °F), he would win. If the temperature change were between 0.2 °C (0.36 °F) and 0.4 °C (0.72 °F) the bet would be off, and if the temperature change were 0.4 °C (0.72 °F) or greater, Annan would win. He would take 2 to 1 odds.[28]

Of the Kyoto Accord, he claims there is no "controversy over the fact that the Kyoto Protocol, itself, will do almost nothing to stabilize CO2. Capping CO2 emissions per unit of electricity generated will have a negligible impact on CO2 levels."[29]

He frequently speaks out against the IPCC position that significant global warming is very likely caused by humans (see global warming) although he accepts that the warming has occurred, saying global mean temperature is about 0.6 degrees Celsius higher than it was a century ago.[14] A Spiegel article on the 2007 IPCC Working Group I report included a discussion of Lindzen's critical views on the IPCC.[30] The writer of article Uwe Buse concluded "Lindzen's arguments sound convincing, but they are still nothing but claims, popular theories as opposed to a transparent global process [the IPCC report], a global plebiscite among climate researchers."

Lindzen has been characterized as a contrarian, in relation to climate change and other issues.[31][32][33] Lindzen's graduate students describe him as "fiercely intelligent, with a deep contrarian streak." [34] This characterization has been linked to Lindzen's view that lung cancer has only been weakly linked to smoking. Writing in Newsweek, Fred Guterl stated "Lindzen clearly relishes the role of naysayer. He'll even expound on how weakly lung cancer is linked to cigarette smoking. He speaks in full, impeccably logical paragraphs, and he punctuates his measured cadences with thoughtful drags on a cigarette"[35] – an observation that was later echoed by Robyn Williams.[36]

^ The NAS panel said on the matter that "The committee finds that the full IPCC Working Group I (WGI) report is an admirable summary of research activities in climate science, and the full report is adequately summarized in the Technical Summary. The full WGI report and its Technical Summary are not specifically directed at policy. The Summary for Policymakers reflects less emphasis on communicating the basis for uncertainty and a stronger emphasis on areas of major concern associated with human-induced climate change. This change in emphasis appears to be the result of a summary process in which scientists work with policy makers on the document. Written responses from U.S. coordinating and lead scientific authors to the committee indicate, however, that (a) no changes were made without the consent of the convening lead authors (this group represents a fraction of the lead and contributing authors) and (b) most changes that did occur lacked significant impact."